Shaft furnace shell cooling system

ABSTRACT

A cooling system for a shaft furnace having horizontal rows of stave coolers installed between the outer shell and the inner refractory lining. The upper ends of each row of coolers are spaced from the furnace shell a greater distance than the lower ends of the coolers of the next higher row.

United States Patent Inventor William G. Seacrest Coopersburg, Pa.

Appl. No. 776,719

Filed Nov. 18,1968

Patented Jan. 12, 1971 Assignee Bethlehem Steel Corporation acorporation of Delaware SHAFT FURNACE SHELL COOLING SYSTEM 5 Claims, 3Drawing Figs.

US. Cl 266/32,

lnt. c1 C2lb 7/10 Field of Search 266/32, 43, 25; 263/44; 264/30 [56]References Cited UNITED STATES PATENTS 452,607 5/1891 Hunt 266/322,291,938 8/l942 Agnew 266/43 3,379,427 4/1968 Zherebin et al 266/32Primary ExaminerGerald A. Dost Att0rney.loseph J. OKeefe PATENTED JAN 1212m INVENTOR Will/am G. Seacrcsf SHAFT FURNACE SHELL COOLING SYSTEMBACKGROUND OF THE INVENTION This invention relates to a cooling systemfor shaft furnaces and more particularly to a stave cooler system whichis interposed between the shell and the refractory lining of such afurnace.

High operating temperatures of metallurgical shaft furnaces,particularly blast furnaces, necessitate the use of some manner ofcooling in order to protect the structural integrity of the furnaceshell and to prolong the usable life of the refractory lining.Conventionally, the cooling systems for such furnaces include aplurality of rows of cast copper cooling plates which extendhorizontally through the shell into the refractory lining. A morerecently developed and less frequently used system peripherally coolsshaft furnaces by means of stavetype coolers. These coolers aresometimes referred to as shannon plates, peripheral plates, peripheralcoolers, or bosh or stack staves. Stave coolers are large curved plateswhich extend vertically and circumferentially of theinterior of thefurnace shell to which they are bolted. The rows of coolers are stackedone on top of another, parallel to the furnace shell, and the spacebetween shell and coolers is filled with a grout or synthetic material.

Studies indicate that stave cooler systems have several advantages,e.g., they provide more uniform cooling than systems which utilize themore conventional cast copper coolers; however, there are severalproblems associated with stave cooler systems. The installation of rowsof stave coolers, one on top of another is troublesome, particularly inthe upwardly and inwardly tapering stack section of a shaft furnace. Therelatively smooth surface presented by the stave cooler system does notpromote the formation of a protective layer of hardened slag on theinner surfaces of the coolers after the lining has been worn away. Inaddition, incremental vertical expansion that may occur due tooverheating of one or more coolers is transmitted to coolers of adjacentrows, thereby placing stresses on the entire installation.

SUMMARY OF THE INVENTION It is an object of this invention to provide ashaft furnace cooler system which is simple in design, easy to install,and effective in operation.

Another object of this invention is to provide a shaft furnace stavecooler system which confines incremental vertical expansion of a coolerdue to overheating to the individual overheated cooler.

A further object of this invention is to provide a shaft furnace stavecooler system which will function to promote the formation of aprotective layer of slag on the cooler surfaces when the refractorylining in front of the coolers has been worn away.

The objects of this invention are achieved a in a shaft furnace having aplurality of horizontal rows of stave coolers by spacing the upper endsof the coolers of each row a greater distance from the furnace shellthan the lower ends of the coolers in the next higher row.

BRIEF DESCRIPTION OF THE DRAWING Referring to the drawing:

FIG, 1 is a view in longitudinal section of a portion of a blast furnaceembodying the present invention.

FIG. 2 is an enlarged view of a portion of the furnace of FIG. 1 showingthe brick lining removed and the stave coolers exposed.

FIG. 3 is an enlarged view, partly in section, taken on the line 3-3 ofFIG. 2.

PREFERRED EMBODIMENT OF THE INVENTION Referring to the drawing there isshown in FIG. 1 a metallurgical blast furnace having hearth 11, bosh 12,and stack 13. Stack 13 comprises the usual metal jacket or shell 14which extends upwardly from mantle l5 and is lined with refractorybricks 16. The upper portion of stack 13 is protected from high furnaceoperating temperatures by means of vertically spaced circumferentialrows of conventional cast copper coolers 17 set radially into the liningand suitably mounted at their outer ends in shell 14. The lower portionof stack 13, sometimes referred to as the hot zone, is protected byperipheral cooling system of 18 of this invention.

Cooling system 18 comprises a pluralityof circumferential rows 19A to19H of stave coolers 20, which may be of any 7 convenient height H.

Each stave cooler 20 has top 21, bottom 22, sides 23, inner orrefractory side surface 24 and outer or shell side surface 25. Securedto shell side surface 25 of each cooler is water circulating conduit 26.Water inlet pipe 27, from a source not shown, is connected to one end ofconduit 26 and water discharge pipe 28 is connected to the other end ofthe conduit. Water inlet and discharge pipes 27 and 28, respectively,extend through openings 29 in shell 14 which are sealed in a convenientmanner.

Except for coolers 20 in bottom row 19A which extend upwardly frommantle 15, coolers 20 of rows l9Bl9H rest upon brackets 30 which arearranged in a plurality of vertically spaced circumferential rows, aportion of which are shown in FIG. 2 as rows 31B, 31C, and 31D thatsupport cooler rows 19B, 19C and 19D, respectively. Bracket rows, as forexample rows 31B, 31C and 31D, are spaced apart a distance D along shell14. Brackets 30 are joined to shell 14 in any suitable manner; as bywelding, and each bracket is separated from adjoining ones in the samerow by a gap 32 in order to avoid the possibility of stresses being setup in the shell in the event a bracket becomes overheated. The bottoms22 of staves 20 in a row, except for the staves of bottom row 19A, arespaced from the inner surface of shell 14 a distance d, as shown inFIGS. 2 and 3, and in this space closure plate 33 extends across gaps 32for reasons hereinafter explained.

Staves 20 of bottom row 19A extend vertically upward from mantle 15 tobrackets 30 of bracket row 31B. The inner surfaces of staves 20 of row19A, adjacent their tops, are close to or in contact with the inner endsof brackets 30 of row 31B, and the tops 21 of these staves are slightlyabove the topsurface of these brackets and overlap the lower innersurfaces 24 of staves 20 of stave row 19B, thenext higher row. Staves 20of second row 19B extend from the top surfaces of brackets 30 of row 31Bupwardly and inwardly of the furnace to brackets 30 of the next higherrow 31C. The outer surfaces 25 of staves 20 of row 19B, adjacent theirtops, are close to or in contact with the inner ends of brackets 30 ofrow 31C, and the tops 21 of these staves are slightly above the topsurfaces of the brackets and overlap the lower inner surfaces 24 ofstaves 20 of stave row 19C, the next higher row. In like fashion, staves20 of the remaining stave rows l9C-l9H extend from the top surfaces oftheir respective supporting brackets 30 upwardly and inwardly of thefurnace to the next higher row of supporting brackets and overlap thebottoms of the staves 20 of the next higher row. Staves 20 are securedin place by means of bolts 34 which pass through openings-35 in shell 14that are sealed in any convenient way. Any spaces between coolers arecaulked with a high temperature caulking material such as asbestos ropeand the space 36 between the outer surfaces 25 of staves 20 and theinner surface of shell 14 is filled with a castable material 36, as therows of coolers are set in place.

In the above described stave cooling system of this invention, theheight H of staves 20 is greater than the distance D between rows ofbrackets 30 so that the upper ends of staves 20 of each row of stavesoverlap brackets 30 which support the next higher row of staves. Staves20, except for the staves in bottom row 19A, have their upper endsspaced a greater distance from shell 14 than their lower ends, and theupper ends of staves 20 of each row are farther from shell 14 than thelower ends of staves 20 of the next higher row. As viewed from theinterior of the furnace, the upper ends of a row of staves overlap thelower ends of the staves of the next higher shell. in addition, theinverted shingle effect of the stave coolers confines local verticalexpansion to a sn single stave and reduces critical installationtolerance. Finally, the upper surfaces 21 of staves 20 provide a shelf,initially to support refractory bricks 16 of the lining, and when thesehave worn away, to assist in the formation of a protective layer ofhardened slag on the tops 21 and inner surfaces 24 of exposed staves. iI claim: p l. A cooling system for a stack furnace having an outer shelland an inner refractory lining, said system comprising:

a. a first row of stave coolers and a second row of stave coolerspositioned above said first row, interposed between said shell and saidrefractory lining,

b. said first row of stave coolers having the upper ends thereof spaceda greater distance from said stack shell than the lower ends of saidsecond row of stave coolers,

c. means to support each said row of stave coolers.

2. The cooling system of claim 1 wherein the upper ends of said firstrow of stave coolers and the lower ends of said second row of stavecoolers overlap.

3. The cooling system of claim 1 wherein said'first row of stave coolershave the upper ends thereof spaced from said furnace shell a greaterdistance than the lower ends thereof.

4. The cooling system of claim 1 wherein each said support means for arow of said stave coolerscomprises a structural member secured to theinner surface of said shell and extending inwardly therefrom.

5. The cooling system of claim 4 wherein the distance between saidsupport members for said first and second rows of stave coolers is lessthan the height of said cooler plates of said first row.

1. A cooling system for a stack furnace having an outer shell and aninner refractory lining, said system comprising: a. a first row of stavecoolers and a second row of stave coolers positioned above said firstrow, interposed between said shell and said refractory lining, b. saidfirst row of stave coolers having the upper ends thereof spaced agreater distance from said stack shell than the lower ends of saidsecond row of stave coolers, c. means to support each said row of stavecoolers.
 2. The cooling system of claim 1 wherein the upper ends of saidfirst row of stave coolers and the lower ends of said second row ofstave coolers overlap.
 3. The cooling system of claim 1 wherein saidfirst row of stave coolers have the upper ends thereof spaced from saidfurnace shell a greater distance than the lower ends thereof.
 4. Thecooling system of claim 1 wherein each said support means for a row ofsaid stave coolers comprises a structural member secured to the innersurface of said shell and extending inwardly therefrom.
 5. The coolingsystem of claim 4 wherein the distance between said support members forsaid first and second rows of stave coolers is less than the height ofsaid cooler plates of said first row.